TGC Industries Set to Join Russell 3000(R) Index

PLANO, Texas, June 24 /PRNewswire-FirstCall/ -- TGC Industries, Inc. (Nasdaq:
TGE) announced today that it is set to join the broad-market Russell 3000(R)
Index when Russell Investments ("Russell") reconstitutes its comprehensive set
of U.S. and global equity indexes on June 26, 2009, according to a preliminary
list of additions posted on June 12, 2009 at www.russell.com. Inclusion in
the Russell 3000 Index indicates that TGC Industries, based upon its total
market capitalization, will also automatically be included in the widely
followed Russell 2000(R) Index for U.S. small-cap stocks.

The annual reconstitution of Russell's U.S. indexes captures the 4,000 largest
U.S. stocks as of the end of May, ranking them by total market capitalization.
Membership in the Russell 3000 Index, which remains in place for one year,
means automatic inclusion in either the large-cap Russell 1000(R) Index or
small-cap Russell 2000 Index, as well as the appropriate growth and value
style indexes. Russell determines membership for its equity indexes primarily
by objective, market-capitalization rankings and style attributes. The Russell
3000 Index also serves as the U.S. component of the Russell Global(R) Index,
which Russell launched in 2007. The Russell indexes are widely used by
investment managers and institutional investors for index funds and as
benchmarks for both passive and active investment strategies. An
industry-leading $4 trillion in assets currently are benchmarked to them.

TGC Industries, Inc., based in Plano, Texas, with branch offices in Houston,
Oklahoma City and Denver, is one of the leading providers of seismic data
acquisition services throughout the continental United States.

CONTACTS: Wayne Whitener
Chief Executive Officer
TGC Industries
(972) 881-1099

Jack Lascar / Karen Roan
DRG&E (713) 529-6600

SOURCE TGC Industries, Inc.

Wayne Whitener, Chief Executive Officer of TGC Industries, +1-972-881-1099; or
Jack Lascar or Karen Roan, both of DRG&E, +1-713-529-6600, for TGC Industries,
Inc.